According to Netanel, one often-overlooked aspect of the opinion is that the Court explicitly identified fair use as an essential “First Amendment accommodation” that cannot be disturbed if copyright law is to survive First Amendment scrutiny. In the process, the Court may have poked a hole in the already shaky constitutional justifications for anti-user sections of copyright law.

First things first: the opinion in Golan v. Holder, released the same day as the historic anti-SOPA blackout protests, was definitely bad for the public domain. At issue was a law that restored copyright restrictions on millions of non-U.S. works that had already become part of the public domain for a variety of reasons, such as the copyright owner’s failure to comply with various formalities. The petitioner Lawrence Golan, a music professor and conductor adversely affected by that law, argued that by destabilizing the public domain that law impinged on his free speech interest in using those works. In its disagreement, the Court said that fostering the public domain is not a requirement for a copyright law to be constitutional. But, importantly, it also said that fair use is such a requirement.

That may turn out to be a bright spot in the decision. After all, we've seen copyright enforcement that doesn't acknowledge the "safety valve" of fair use, and the result is silenced or chilled speech. Whether it's individuals and organizations abusing the takedown process as the shortest road to censorship, or overzealous algorithmic enforcement that ensnares legitimate expression, a failure to consider fair use has serious consequences for speech.

So it's actually a good thing that, as Netanel argues, the Court's precedent has changed significantly with Golan. Prior to the Golan decision, there was some question as to whether undermining fair use right might raise a constitutional issue. By contrast, Golan explicitly calls out fair use as one of the “traditional contours” of copyright that must be accommodated to bring copyright law into line with the First Amendment.

This point is important, because there are currently copyright laws on the books that do not adequately accommodate fair uses. Chief among them is the Digital Millenium Copyright Act—specifically section 1201, the "anti-circumvention clause" that prohibits users from interfering with "digital rights management" software designed to control access to a copyrighted work, and from distributing tools that could help others get around those software controls. The restrictions in section 1201 of the DMCA apply even if the user's purpose in circumventing the software would otherwise be considered a fair use, leading to all sorts of unintended consequences.

Courts have relied on the earlier Supreme Court precedent to dismiss legitimate concerns about that particular law. In a case concerning the distribution of software that could read DVDs despite their "content scrambling system," a federal judge in New York acknowledged that there is no fair use defense in the DMCA, but dismissed claims that the lack of that defense made the law unconstitutional. Instead, he noted that the "Supreme Court has never held that fair use is constitutionally required."

Netanel makes the compelling argument that Golan changed the rules. Under Golan, laws like the DMCA's anti-circumvention clause may be unconstitutional. Indeed, even the other safeguards found in the DMCA—like the triennial rulemaking procedure for excluding certain forms of circumvention for certain purposes—are too limited to bring the DMCA into line with the First Amendment.

But the argument extends beyond anti-circumvention clauses to other areas of copyright law, too. For example, as Netanel points out, proposals from the copyright lobby to eliminate "safe harbors" and expand liability for Internet service providers may also be problematic. Expanding intermediary copyright liability could result in "censorship by proxy," where risk-averse platforms could refuse to carry First Amendment-protected speech just because it relies on fair use.

Fair use has always been a critical component of copyright law, and if Netanel's argument is correct, that's now got firm constitutional recognition. So what comes next? It's up to us to fix existing copyright law to include those protections for speech, and reject new laws and international agreements that don't.